Many home care and personal care formulations seek to deliver benefit agents to substrates such as textiles, hard surfaces, hair and skin. Encapsulation of the benefit agent in particles has been proposed as a means of enhancing delivery. Encapsulation of perfumes has generated particular interest and activity in recent years.
However, there is still much room for improvement as consumer preference for improved fragrance perception at multiple stages of the wash process, such as at the end of the wash, and for ever longer lasting perfume performance, drives commercial interest in this area.
Leakage of encapsulates remains a problem which not only causes reduced performance but also restricts the ingredients that can be stably encapsulated.
Melamine formaldehyde capsules are known but, disadvantageously, need to be used in conjunction with a formaldehyde scavenger.
US 2008 146478 (International Flavors and Fragrances Inc) discloses a microcapsule comprising an active material, a nanoscaled material and an encapsulating polymer. The encapsulating polymer is selected from the group consisting of a vinyl polymer, an acrylate polymer, an acrylate acrylamide copolymer, melamine-formaldehyde polymer, urea-formaldehyde polymer and mixtures thereof to form a polymer encapsulated fragrance. See claims 1, 2 and sections [0111] and [0113].
US 2004 071742 (International Flavors and Fragrances Inc) discloses a composition comprising: a fragrance material; said fragrance material encapsulated by a polymer to provide a polymer encapsulated fragrance; the polymer encapsulated fragrance is further coated by a cationic polymer.
US 2004 072719 (International Flavors and Fragrances Inc) discloses a composition comprising: a fragrance material; said fragrance material encapsulated by a polymer to provide a polymer encapsulated fragrance; the polymer encapsulated fragrance is further coated by a polyamine polymer.
U.S. Pat. No. 5,460,817 (Allied Colloids Ltd) discloses a particulate composition comprising particles having an anhydrous core comprising (a) a solid matrix polymer and an active ingredient distributed throughout the solid matrix polymer and (b) an outer protective coacervated polymer shell. The outer shell is formed of a cross-linked polymer (Polyvinyl alcohol).
WO 92/06672 (Revlon Inc.) discloses a microencapsulate comprising one or more antiperspirant salts encapsulated within a shell wall which is susceptible to osmotic, enzymatic, or electrolytic degradation, or degradation due to water solubility of the shell wall.
We have now surprisingly found that the use of crosslinking agent comprising a mixture of dextrans having different molecular weights, and the cross-linked mPVOH capsules thus produced, leads to marked improvement in deposition efficiency and a corresponding consumer perceivable increase in benefit delivery.
Advantageously, the new capsules are made substantially from renewable feedstocks, which helps to reduce environmental impact.